Quail Model Research Articles

The quail anatomy portal

The Japanese quail is a widely used model organism for the study of embryonic development; however, anatomical resources are lacking. The Quail Anatomy Portal (QAP) provides 22 detailed three-dimensional (3D) models of quail embryos during development from embryonic day (E)1 to E15 generated using optical projection tomography. The 3D models provided can be virtually sectioned to investigate anatomy. Furthermore, using the 3D nature of the models, we have generated a tool to assist in the staging of quail samples. Volume renderings of each stage are provided and can be rotated to allow visualization from multiple angles allowing easy comparison of features both between stages in the database and between images or samples in the laboratory. The use of JavaScript, PHP and HTML ensure the database is accessible to users across different operating systems, including mobile devices, facilitating its use in the laboratory.The QAP provides a unique resource for researchers using the quail model. The ability to virtually section anatomical models throughout development provides the opportunity for researchers to virtually dissect the quail and also provides a valuable tool for the education of students and researchers new to the field.Database URL: http://quail.anatomyportal.org(For review username: demo, password: quail123)

Xenogeneic Transfer of Adult Quail (Coturnix coturnix) Spermatogonial Stem Cells to Embryonic Chicken (Gallus gallus) Hosts: A Model for Avian Conservation1

As advanced reproductive technologies have become routine for domesticated species, they have begun to be applied in the field of endangered species conservation. For avian conservation, the most promising technology is the transfer of germ stem cells of exotic species to domestic hosts for the production of gametes. In this study, adult quail (model for exotic species) spermatogonial stem cells were xenogeneically transferred to stages 14-17 chicken host embryos. Fluorescent cellular dyes, quail-specific antibodies, and quail-specific quantitative PCR confirmed donor cell migration to and colonization of the host gonadal ridge. Donor-derived cells were observed by fluorescent microscopy in the caudal area as early as 2 h after injection, in the gonadal ridge at 4 h after injection, as well as in the gonads of stages 35-38 host embryos. Four of eight donor-derived cell flow cytometry-positive host gonads were confirmed by quantitative PCR using quail-specific primers. There was no statistically significant effect of host stage of injection, host gonad isolation stage, or host sex on the number of hosts positive for donor cells or the percent of donor-derived cells per positive gonad. Donor-derived cells isolated from stages 35-38 host gonads costained with the germ stem cell marker SSEA-1, indicating that the donor-derived cells have maintained stem cell-ness. This is the first study to suggest that it is feasible to rescue adult germ stem cells of deceased birds to prolong the reproductive lifespan of critically endangered species or genetically valuable individuals by transferring them to an embryonic chicken host.

Transgenesis and imaging in birds, and available transgenic reporter lines

Avian embryos are important model organism to study higher vertebrate development. Easy accessibility to developing avian embryos enables a variety of experimental applications to understand specific functions of molecules, tissue-tissue interactions, and cell lineages. The whole-mount ex ovo culture technique for avian embryos permits time-lapse imaging analysis for a better understanding of cell behaviors underlying tissue morphogenesis in physiological conditions. To study mechanisms of blood vessel formation and remodeling in developing embryos by using a time-lapse imaging approach, a transgenic quail model, Tg(tie1:H2B-eYFP), was generated. From a cell behavior perspective, Tg(tie1:H2B-eYFP) quail embryos are a suitable model to shed light on how the structure and pattern of blood vessels are established in higher vertebrates. In this manuscript, we give an overview on the biological and technological background of the transgenic quail model and describe procedures for the ex ovo culture of quail embryos and time-lapse imaging analysis.

Dietary lutein and fish oil interact to alter atherosclerotic lesions in a Japanese quail model of atherosclerosis

Interactions between concentration of dietary lutein and fish oil in diets on atherosclerosis incidences were studied in a cholesterol-induced-atherosclerosis (CIA) model. CIA Japanese quail were fed a basal diet with three amounts of lutein (0, 25 and 50 mg/kg diet) and two amounts of fish oil (3% and 6%) in a 3 × 2 factorial in five replications. Samples were collected at 24 and 27 weeks of age. Atherosclerosis lesions in the dorsal aorta were measured by histochemistry sectioning. At 27 weeks of age, increasing dietary fish oil content to 6% decreased (p < 0.01) the atherosclerotic lesions only in the 0 mg lutein supplemented groups. At 27 weeks of age, increasing dietary fish oil content to 6% increased the atherosclerotic lesion score when lutein was supplemented at either 25 or 50 mg/kg feed. Aorta and liver lutein content increased (p < 0.01) with increasing dietary lutein content at 27 weeks of age. Increasing dietary fish oil content to 6% increased (p < 0.01) the aorta fat content by twofold and decreased (p < 0.01) the liver fat by 26% at 27 weeks of age. Increasing the dietary fish oil content to 6% increased (p = 0.01) the total PUFA and decreased (p = 0.03) the total mono unsaturated fatty acids content of the aorta at 27 weeks of age. At 27 weeks of age, increasing dietary fish oil content to 6% decreased the amount of TBARS (p = 0.01) and IL-1 mRNA (p < 0.01) only in the 0 mg lutein supplemented groups. Increasing dietary fish oil content to 6% increased the amount of TBARS and IL-1 mRNA of the aorta when lutein was supplemented at either 25 or 50 mg/kg diet. Dietary lutein supplementation decreased atherosclerosis lesions only at low levels of dietary polyunsaturated fatty acids.

Effects of oral administration of L-methionine on activity/rest rhythm

We describe a chronobiological study of the effects of the oral administration of the essential amino acid L-methionine to common quail ( Coturnix coturnix ). This amino acid is a precursor of the neurotransmitter acetylcholine which is responsible for controlling and maintaining wakefulness through the ventrolateral pre-optic area of the hypothalamus and controlling the REM sleep in the nucleus reticularis pontinus oralis (NRPO). The quail model was chosen as these birds are monophasic and active by day, as are humans. The animals were kept under a constant 12h:12h light/dark cycle, fed ad libitum and housed in separate cages equipped for activity recording. Methionine was administered daily (1 h before lights off) for 1 week (chronic treatment), with the birds divided into 4 groups: a capsule with 15 mg of L-methionine (Met15 treatment group); a capsule with 30 mg of L-methionine (Met30 treatment group); a capsule with methylcellulose as excipient (control group); no capsule (basal group). In addition, we compared the first day of treatment (acute experiment) with the basal and control results. Actimetry (DAS24) was used to quantify the activity data, and the sleep/wake rhythm was analyzed using the Ritme software package. The statistical analysis of the activity data was descriptive (+/- SD) and inferential (Tukey test). The data showed increased (p<0.05) mean diurnal activity pulses in the Met30 group versus the other groups in both the acute and the chronic experiments. No changes were found in nocturnal activity. The chronobiological analysis showed a significant increase in the MESOR parameter of the Met30 group in both chronic and acute experiments versus the other groups. The acrophase showed no significant changes, in all groups being at around 13:45 h. In conclusion, the oral administration of L-methionine increased diurnal activity; probably due to the stimulating neuromodulatory action of acetylcholine.

Treatment of Non-alcoholic Fatty Liver Disease with the Carotenoid Zeaxanthin in a Quail Model

Purpose: Non-alcoholic fatty liver disease (NAFLD) is associated with insulin resistance and the development of Type II diabetes mellitus. Inflammation and oxidative stress have been implicated in the development of NAFLD and metabolic syndrome. We have previously shown that the carotenoid zeaxanthin showed a strong anti-oxidant and protective effect in a model of methionine-choline deficiency-induced steatohepatitis. [1] In this study we assessed the effects of zeaxanthin treatment on high fat diet-induced fatty liver disease and insulin resistance. Methods: Japanese quails (an established animal model for zeaxanthin) were reared on a carotenoid-deficient diet and then fed additional corn oil (18cc/ gr of feed, corresponding to a 33% increase in dietary fat consumption) for 4 weeks. Four experimental groups were analyzed in this study: quails not subjected to corn oil treatment (carotenoid-deficient diet control= CTRL, n=10), quails fed with corn oil (high fat diet group=HF, n=10), quails fed with HF diet and treated with 12.5mg/kg zeaxanthin administered orally every other day (HF+12.5, n=10) and quails fed with HF diet and treated with 25mg/kg zeaxanthin administered orally every other day (HF+25, n=10). At the end of treatment the animals were sacrificed and the livers and plasma were collected for histologic analysis and metabolic screening, respectively. Results: We found that only the HF group displayed steatosis (mild). The HF group also had circulating levels of triglycerides and insulin both significantly increased (approximately 3-fold, p<0.01) above CTRL. Treatment with zeaxanthin was able to significantly reduce insulin levels in a dose dependent manner (p<0.01) for HF+12.5 and HF+25 compared to HF. Treatment with HF+25 was able to significantly reduce triglyceride levels (p<0.01) compared to HF (see Table).Table: Table. Metabolic outcomes by treatment groupConclusion: The results of this study suggest that treatment with the carotenoid zeaxanthin may be beneficial in preventing the development of insulin resistance and hypertriglyceridemia associated with NAFLD and metabolic syndrome.

Abdominal Fat Accumulation with Hyperuricemia and Hypercholesterolemia Quail Model Induced by High Fat Diet

To establish abdominal fat accumulation with hyperuricemia and hypercholesterolemia quail model fed with high fat diet. And then to investigate the pathological characteristics of this quail model. Thirty Longcheng quails were randomly divided into two groups: control group and model group (n=15). The control group quails were fed with normal diet and model group quails were fed with high fat diet for 14 days. After a 12-hour overnight fast, liver and abdominal fat at euthanasia as well as serum were collected. The levels of serum uric acid, total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglyceride, free fatty acid (FFA), and blood glucose were assayed. The activity changes of adenosine deaminase (ADA), xanthine oxidase (XOD), lipoprotein lipase (LPL), hepatic lipase (HL), and fatty acid synthetase (FAS) were analyzed. Compared with control group, the abdominal fat content (0.74+/-0.63 vs. 1.36+/-0.65 g, P<0.05) and abdominal fat index (0.44%+/-0.30% vs. 0.85%+/-0.30%, P<0.01) as well as live lipid index (3.61%+/-0.65% vs. 11.33%+/-2.14%, P<0.01) in model group significantly increased; the levels of serum uric acid (210.61+/-94.76 vs. 304.25+/-141.94 micromol/L, P<0.05), total cholesterol (4.20+/-0.51 vs. 20.10+/-11.25 mmol/L, P<0.01), LDL-C (1.16+/-0.29 vs. 10.78+/-6.48 mmol/L, P<0.01), and FFA (0.39+/-0.14 vs. 0.55+/-0.15 mmol/L, P<0.01) in model group significantly increased; HDL-C (5.85+/-0.95 vs. 4.14+/-2.03 mmol/L, P<0.05) significantly decreased; the levels of triglyceride and blood glucose had no significant changes (P>0.05); the activities of ADA (9.71+/-3.05 vs. 17.19+/-5.10 U/ml, P<0.01) and XOD (10.58+/-6.88 vs. 19.22+/-9.44 U/L, P<0.01) in model group significantly increased; and FAS, LPL, HL had no significant changes (P>0.05). High fat diet can induce abdominal fat accumulation with hyperuricemia and hypercholesterolemia quail model. The changes of uric acid and lipid metabolic enzyme activities may be the pathological mechanism of abdominal fat accumulation with hyperuricemia and hypercholesterolemia.

Developmental stages of Coturnix coturnix japonica, the Japanese quail

Coturnix coturnix japonica (Japanese Quail) is an avian species that has been extensively used in developmental studies for many years. Unlike the domestic chicken, Gallus gallus domesticus, the development of the quail has not been accurately staged, despite being used as an important developmental tool. The chick was accurately staged over 50 years ago in a seminal paper by Hamburger and Hamilton and although there have been several papers looking at developmental stages of the quail, the process has not been comprehensive or definitive and therefore researchers have often used the chick staging criteria. One of the most obvious and dramatic differences between quail and chick is hatching times, with the quail hatching some 4‐5 days before the chick. This more rapid developmental cycle means that the use of the Hamburger and Hamilton stage series for all quail developmental studies may not be advantageous. Therefore, we have constructed a comprehensive stage series of quail embryo development, which covers the whole incubation period. It is hoped that such a series will provide researchers with an accessible manual, when using the quail model. Funded by Brighton &amp; Sussex Medical School.

Prevention of hypercholesterolemia and atherosclerosis in the hyperlipidemia- and atherosclerosis-prone Japanese (LAP) quail by taurine supplementation

The effects of taurine supplementation on the serum cholesterol levels and the progression of atherosclerosis were investigated in the hyperlipidemia- and atherosclerosis-prone Japanese (LAP) quail. The ingestion of a high-cholesterol diet containing 1% cholesterol by LAP quails for 60 days resulted in a marked elevation in serum non-HDL cholesterol and triglyceride, as well as severe aortic lesions with lipid droplets. An immunohistochemical study showed that the lesion consisted of mainly lipid-rich macrophages and T cells. Sixty-day taurine supplementation (1% in drinking tap water) to LAP quails fed high-cholesterol diet containing 1% cholesterol significantly reduced serum non-HDL cholesterol from 4,549 to 2,350 mg/dl. The serum triglyceride level also decreased after taurine supplementation from 703 to 392 mg/dl. Although the HDL cholesterol level significantly decreased due to the high-cholesterol diet, it recovered to the control level fed a regular diet in response to taurine. Bile acid production was stimulated and hepatic cholesterol was reduced by taurine supplementation. A quantitative analysis using aortic cross-sections showed that areas of oil-red O positive lipid accumulation significantly decreased by 74% after taurine supplementation. These results demonstrated the lipid-lowering and anti-atherosclerotic effects of taurine in a diet-induced hyperlipidemic LAP quail model. The prevention of atherosclerosis by taurine is mainly attributed to an improvement in the serum cholesterol and triglyceride levels, which may be related to changes in the hepatic cholesterol metabolism.

Efficacy of voriconazole in Japanese quail (Coturnix japonica) experimentally infected with Aspergillus fumigatus

Aspergillus fumigatus causes disease in birds. Our objectives were to determine pharmacokinetic parameters and evaluate efficacy of voriconazole (VCZ) in a novel experimental quail model. After a single oral VCZ dose of 20 or 40 mg/kg, plasma concentrations peaked 2 h postdose (5.8 and 6.9 microg/ml) and remained above 0.5 microg/ml for 4 and 12 h postdose, respectively. For the efficacy study, ten-day-old Japanese quail (n = 60) were infected intratracheally with A. fumigatus conidia. Daily oral VCZ at 20 or 40 mg/kg was initiated 24 h postinfection (PI); infected diluent-treated birds were given de-ionized water orally. Preassigned birds were euthanized on days 5 or 10 PI. VCZ at 40 mg/kg prolonged survival compared to 20 mg/kg or diluent-treatment (P < 0.05) and lungs from birds given VCZ at 40 mg/kg had fewer colony forming units (CFU) than diluent-treated (P = 0.03). At day 10 PI, birds treated with VCZ at 20 mg/kg had significantly fewer fungi in the lungs as demonstrated by methenamine silver stain (P = 0.017) or immunohistochemistry, as compared to diluent-treated (P = 0.034). Histopathologically, VCZ-treated birds did not have necrotic lesions and showed a trend toward fewer with acute inflammatory changes. VCZ at 40 mg/kg was efficacious in quail with experimental pulmonary aspergillosis.

Retinoic acid is required for specification of the ventral eye field and for Rathke's pouch in the avian embryo

We have investigated the role of retinoic acid (RA) in eye development using the vitamin A deficient quail model system, which overcomes problems of retinoic acid synthesising enzyme redundancy in the embryo. In the absence of retinoic acid, the ventral optic stalk and ventral retina are missing, whereas the dorsal optic stalk and dorsal retina develop appropriately. Other ocular abnormalities observed were a thinner retina and the lack of differentiation of the lens. In an attempt to explain this, we studied the expression of various dorsally and ventrally expressed genes such as Pax2, Pax6, Tbx6, Vax2, Raldh1 and Raldh3 and noted that they were unchanged in their expression patterns. In contrast, the RA catabolising enzymes Cyp26A1 and Cyp26B1 which are known to be RA-responsive were not expressed at all in the developing eye. At much earlier stages, the expression domain of Shh in the prechordal plate was reduced, as was Nkx2.1 and we suggest a model whereby the eye field is specified according to the concentration of SHH protein that is present. We also describe another organ, Rathke's pouch which fails to develop in the absence of retinoic acid. We attribute this to the down-regulation of Bmp2, Shh and Fgf8 which are known to be involved in the induction of this structure.

Retinoids control anterior and dorsal properties in the developing forebrain

We have previously shown that retinoic acid (RA) synthesized by the retinaldehyde dehydrogenase 2 (RALDH2) is required in forebrain development. Deficiency in RA due to inactivation of the mouse Raldh2 gene or to complete absence of retinoids in vitamin-A-deficient (VAD) quails, leads to abnormal morphogenesis of various forebrain derivatives. In this study we show that double Raldh2/Raldh3 mouse mutants have a more severe phenotype in the craniofacial region than single null mutants. In particular, the nasal processes are truncated and the eye abnormalities are exacerbated. It has been previously shown that retinoids act mainly on cell proliferation and survival in the ventral forebrain by regulating SHH and FGF8 signaling. Using the VAD quail model, which survives longer than the Raldh-deficient mouse embryos, we found that retinoids act in maintaining the correct position of anterior and dorsal boundaries in the forebrain by modulating FGF8 anteriorly and WNT signaling dorsally. Furthermore, BMP4 and FGF8 signaling are affected in the nasal region and BMP4 is ventrally expanded in the optic vesicle. At the optic cup stage, Pax6, Tbx5 and Bmp4 are ectopically expressed in the presumptive retinal pigmented epithelium (RPE), while Otx2 and Mitf are not induced, leading to a dorsal transdifferentiation of RPE to neural retina. Therefore, besides being required for survival of ventral structures, retinoids are involved in restricting anterior identity in the telencephalon and dorsal identity in the diencephalon and the retina.

Bmp2 and Gata4 function additively to rescue heart tube development in the absence of retinoids

We used the vitamin A-deficient (VAD) quail model to investigate the retinoid-dependent mechanism that regulates heart tube development. We showed previously that decreased levels of Gata4 in cardiogenic mesoderm and endoderm correlate with the cardiomyopathy caused by VAD, but that this could be rescued by transplanting normal anterior endoderm. Bmp2 is a known cardiogenic factor that is expressed normally in lateral plate mesoderm and cardiac-associated pharyngeal endoderm. Here we show that (like Gata4) transcripts encoding Bmp2 and BMP-dependent signaling activity are decreased throughout the heart-forming region of the VAD embryo. Addition of Bmp2 protein or forced expression of Gata4 in cultured VAD embryos leads to a partial rescue of the cardiomyopathy, and addition of both Bmp2 and Gata4 has an additive positive effect. Our data are consistent with a requirement for retinoid signaling to maintain expression of Bmp2, which regulates Gata4, and in addition acts with Gata4 to regulate genes important for normal morphogenesis of the primitive heart tube.

Experimental study of osthole on treatment of hyperlipidemic and alcoholic fatty liver in animals

To evaluate the effects of osthole on fatty liver, and investigate the possible mechanism. A quail model with hyperlipidemic fatty liver and rat model with alcoholic fatty liver were set up by feeding high fat diet and alcohol, respectively. These experimental animals were then treated with osthole 5-20 mg/kg for 6 wk, respectively. Whereafter, the lipid in serum and hepatic tissue, and coefficient of hepatic weight were measured. After treatment with osthole the levels of serum total cholesterol (TC), triglyceride (TG), lower density lipoprotein-cholesterol (LDL-C), coefficient of hepatic weight, and the hepatic tissue contents of TC and TG were significantly decreased. The activity of superoxide dismutase (SOD) in liver was improved. In alcohol-induced fatty liver rats, the level of malondialdehyde (MDA) in liver was decreased. In high fat-induced fatty liver quails, glutathione peroxidase (GSH-PX) in liver was significantly improved. The histological evaluation of liver specimens demonstrated that the osthole dramatically decreased lipid accumulation. These results suggested that osthole had therapeutic effects on both alcohol and high fat-induced fatty liver. The mechanism might be associated with its antioxidation.

Sexual fetishism in a quail (Coturnix japonica) model system: Test of reproductive success.

In the present study, the authors explored the reproductive consequences of fetishistic behavior in a previously developed animal model of sexual fetishism (F. Köksal et al., 2004). Male domesticated quail (Coturnix japonica) received sexual conditioning trials in which a terrycloth object (the conditioned stimulus [CS]) was paired with the opportunity to copulate with a female quail (the unconditioned stimulus). Approximately half of the male quail came to copulate with the CS object and were considered to have developed fetishistic behavior. Each of the male quail was then tested with a female quail, whose eggs were incubated to determine rates of fertilization. The CS object was present for 30 s before and during the copulation test. Fetishistic male quail were slower to achieve cloacal contact with the female quail and showed less efficient copulatory behavior. However, they fertilized a greater proportion of eggs than nonfetishistic male quail. These results are unexpected from previous studies of the relationship between reproductive success and copulatory behavior and are discussed in terms of how fetishistic behavior directed toward an inanimate object may modify male-female interactions.

Evidence for Clostridial Implication in Necrotizing Enterocolitis through Bacterial Fermentation in a Gnotobiotic Quail Model

Despite extensive research, the pathogenesis of neonatal necrotizing enterocolitis (NEC) remains elusive. The aim of our work was to investigate the role of bacterial strains involved in NEC in gnotobiotic quails as experimental model. Six groups of germ-free quails that were fed a lactose diet were associated with Klebsiella pneumoniae, Clostridium perfringens, C. difficile, C. paraputrificum, or C. butyricum (two strains). Implantation level, incidence of cecal lesions, production of short-chain fatty acids, and histologic lesions of the cecal wall were investigated. Whatever the strain, the implantation level was high (10(9) UFC/g). Neither K. pneumoniae nor C. difficile induced any cecal lesions. In contrast, the four other clostridial strains led to cecal NEC-like lesions with a variable occurrence: four of 12 quails for C. perfringens, eight of 12 quails for C. paraputrificum, and the same highest value, nine of 12 quails and eight of 10 quails for both C. butyricum strains. Gross aspects of the lesions may be linked to the short-chain fatty acid profiles and/or concentrations: thickening of the cecal wall (C. butyricum and C. perfringens) with high proportion of butyric acid, hemorrhages (C. paraputrificum) with high proportion of iso-butyric acid, and presence of other iso-acids. In addition, C. butyricum was characterized by pneumatosis, linked to a high gas production. Microscopic aspects confirmed the presence of edemas and intramucosa hemorrhages. Clostridia species, whose role is controversial, seem to be strongly implicated in NEC through excessive production of butyric acid as a result of colonic lactose fermentation. These results call for anaerobe detection in feces of infants who have NEC.

The control of morphogen signalling: Regulation of the synthesis and catabolism of retinoic acid in the developing embryo

We consider here how morphogenetic signals involving retinoic acid (RA) are switched on and off in the light of positive and negative feedback controls which operate in other embryonic signalling systems. Switching on the RA signal involves the synthetic retinaldehyde dehydrogenase (RALDH) enzymes and it is currently thought that switching off the RA signal involves the CYP26 enzymes which catabolise RA. We have tested whether these enzymes are regulated by the presence or absence of all- trans-RA using the vitamin A-deficient quail model system and the application of excess retinoids on beads to various locations within the embryo. The Raldhs are unaffected either by the absence or presence of excess RA, whereas the Cyps are strongly affected. In the absence of RA some, but not all domains of Cyp26A1, Cyp26B1 and Cyp26C1 are down-regulated, in particular the spinal cord ( Cyp26A1), the heart and developing vasculature ( Cyp26B1) and the rhombomeres ( Cyp26C1). In the presence of excess RA, the Cyps show a differential regulation- Cyp26A1 and Cyp26B1 are up-regulated whereas Cyp26C1 is down-regulated. We tested whether the Cyp products have a similar influence on these genes and indeed 4- oxo-RA, 4-OH-RA and 5,6- epoxy-RA do. Furthermore, these 3 metabolites are biologically active in that they fully rescue the vitamin A-deficient quail embryo. Finally, by using retinoic acid receptor selective agonists we show that these compounds regulate the Cyps through the RARα receptor. These results are discussed with regard to positive and negative feedback controls in developing systems.

Distinct roles for hindbrain and paraxial mesoderm in the induction and patterning of the inner ear revealed by a study of vitamin-A-deficient quail

The hindbrain and cranial paraxial mesoderm have been implicated in the induction and patterning of the inner ear, but the precise role of the two tissues in these processes is still not clear. We have addressed these questions using the vitamin-A-deficient (VAD) quail model, in which VAD embryos lack the posterior half of the hindbrain that normally lies next to the inner ear. Using a battery of molecular markers, we show that the anlagen of the inner ear, the otic placode, is induced in VAD embryos in the absence of the posterior hindbrain. By performing grafting and ablation experiments in chick embryos, we also show that cranial paraxial mesoderm which normally lies beneath the presumptive otic placode is necessary for otic placode induction and that paraxial mesoderm from other locations cannot induce the otic placode. Two members of the fibroblast growth factor family, FGF3 and FGF19, continue to be expressed in this mesodermal population in VAD embryos, and these may be responsible for otic placode induction in the absence of the posterior hindbrain. Although the posterior hindbrain is not required for otic placode induction in VAD embryos, the subsequent patterning of the inner ear is severely disrupted. Several regional markers of the inner ear, such as Pax2, EphA4, SOHo1 and Wnt3a, are incorrectly expressed in VAD otocysts, and the sensory patches and vestibulo-acoustic ganglia are either greatly reduced or absent. Exogenous application of retinoic acid prior to 30 h of development is able rescue the VAD phenotype. By performing such rescue experiments before and after 30 h of development, we show that the inner ear defects of VAD embryos correlate with the absence of the posterior hindbrain. These results show that induction and patterning of the inner ear are governed by separate developmental processes that can be experimentally uncoupled from each other.

Consequences of endocrine disrupting chemicals on reproductive endocrine function in birds: Establishing reliable end points of exposure

It has been difficult to establish reliable indices of exposure to endocrine disrupting chemicals (EDCs) appropriate for a variety of avian species because of a vast array of reproductive strategies. Data from mammals, reptiles and fish provide insight on likely mechanisms of action for EDCs. However, many of the effects of EDCs are weaker than the actions of the native hormones, making it difficult to assess adverse effects in domestic and wild birds. It is clear that differential sensitivity to EDCs exists across species, due to the timing and mode of exposure, compound toxicity and age of the individual. Our studies on EDCs are conducted in the quail model system, with focus on reproductive endocrine, neuroendocrine and behavioral responses. Studies have included EDC exposure, either by egg injection or via diet. Results from egg injection studies showed the following: (1) estradiol administered by embryonic day 12 demasculinized male sexual behavior, altered hypothalamic neurotransmitters and reduced hen day production and fertility in a dose dependent fashion, (2) methoxychlor (MXC) or vinclozolin impaired male sexual behavior in adult quail and (3) DDE exposure impaired reproductive and immune related end points. Two-generation studies were conducted on Japanese and northern bobwhite quail with dietary methoxychlor (MXC) exposure (0, 5 and 10 ppm) beginning in adults (P1), continuing in their offspring (F1), with F2 offspring raised on control diet. MXC exposure impaired male sexual behavior, hypothalamic catecholamines and plasma steroid hormones. Moreover, MXC exposure had reproductive consequences observable at both the lower and higher doses of MXC in F1 and F2 generations. These data demonstrate that embryonic EDC exposure interferes with sexual differentiation of neural systems that direct reproduction.

Visualising learning goals with the Quail Model

&lt;span&gt;This paper introduces the Quail Model, a device for the classification and visualisation of learning goals. The model is a communication tool that can smoothen the discussion within a course design team, support shared understanding, and improve decision making. Its theoretical background mingles contributions from instructional design (Bloom, Gagné, Merrill) with the insights of an author of philosophy (Lonergan). The paper presents a literature review, the Quail Model and some examples. Reference to a demonstration application is also provided.&lt;/span&gt;